This invention relates to an image scanning unit, and more particularly to, a mechanism for positioning a CCD substrate in image scanning unit of a facsimile machine, a digital copying machine etc.
In such an image scanning unit using one-dimensional CCD, fine positioning of CCD will be necessary as high-resolution and color machines become widely used in future years.
Japanese patent application laid-open No. 60-115904 (1985) discloses a positioning and adjusting mechanism for image sensor which, to solve the problem that fine positioning of image sensor to scanning line cannot be performed because of not having a mechanism to adjust it three-dimensionally and independently, is composed of: a first plate which is engaged to an optical frame to be disposed on the scanning line and is movable up and down to the frame; a second plate which is movable right and left and to the first plate while engaging to the first plate and is movable back and forth to the optical frame; and a third plate which holds an image sensor disposed on its plane facing the second plate and is movable in a fan-shaped range to the second plate, wherein these plates are moved to allow the image sensor to be positioned and adjusted three-dimensionally and independently to the scanning line.
However, the conventional positioning and adjusting mechanism needs to be improved since it is short of degree of freedom on adjustment and furthermore requires a lot of skill for its operation.
Accordingly, it is an object of the invention to provide an image scanning unit that brings facilitation in the positioning adjustment of CCD substrate, enhancing the precision of positioning adjustment and enhancing the efficiency of adjustment work.
According to the invention, an image scanning unit, comprises:
a CCD substrate which is mounted on a block;
three groups of adjustment fastening members to position the CCD substrate in three dimensional directions orthogonal to one another; and
a springy member to press each of the adjustment fastening members against receiving part of each of the adjustment fastening members;
wherein the three groups of adjustment fastening members are composed of a first group of fastening members to conduct the focus adjustment by independently positioning the CCD substrate in a direction perpendicular to the plane of the CCD substrate at both ends of CCD in the longitudinal direction, a second group of fastening members to conduct the sub-scanning adjustment by independently positioning the CCD substrate in a direction orthogonal to the longitudinal direction of the CCD substrate within the plane of the CCD substrate at both ends of CCD in the longitudinal direction, and a third group of fastening member to conduct the main-scanning adjustment by independently positioning the CCD substrate in a direction along the longitudinal direction of the CCD substrate within the plane of the CCD substrate.